Current and historical procedures for the treatment of colon and rectal cancer have been based, for staging purposes, upon the natural history of tumor spread, and thence, upon operative and non-operative options. Operative options generally have looked to the physical location and surgical resection of tumor. A variety of techniques have been brought to bear in the art with the purpose of aiding the surgeon in detecting and localizing neoplastic tissue as part of this surgical procedure. ("Neoplastic tissue", for present purposes, often is referred to as cancerous tissue, though malignant tumor and malignant tumor cells also are found in the terminology of the art. The term "neoplastic tissue" includes all of these.) A substantial amount of effort in aiding the surgeon in locating neoplastic tissue has been through the utilization of radiolabeled antibody for detection purposes. For example, one technique includes the scintillation scanning of patients injected with relatively high energy, e.g. .sup.131 I labeled antibodies. Such photoscanning or scintillation scanning provides scintigrams difficult to interpret because of blood pool background radioactivity. Computer subtraction of radioactive blood pool agents and the use of two labeled antibodies (one specific for the tumor and one non-specific) have been attempted to enhance imaging. Nevertheless, such techniques have been found to provide little, if any, useful information to the surgeon, especially over and above CAT scans, magnetic resonance imagings, and like traditional techniques. Typically, large tumor is readily located by the surgeon by visualization at the operating theater and, in particular, through palpation, i.e. the feel of a tumor as opposed to that of normal tissue. To achieve operative success, however, it is necessary for the surgeon to somehow locate "occult" tumor, i.e. tumor which cannot be found by the conventional surgical procedure of sight and feel. Failure to locate and remove such occult tumor generally will result in the continued growth of cancer in the patient, a condition often misidentified as "recurrent" cancer. In general, conventional diagnostic techniques as, for example, use of the classic gamma camera and the like, fail to find or locate occult tumor. As tumor sites become smaller, the radionucleide concentrations at a given tumor site will tend to be lost, from an imaging standpoint, in the background where blood pool radiation necessarily is present in the patient.
U.S. Pat. No. 4,782,840 by Martin, M. D. and Thurston, Ph.D., entitled "Method for Locating, Differentiating, and Removing Neoplasms, issued Nov. 8, 1988 (the disclosure of which is expressly incorporated herein by reference) reviews such scintillation scanning technique and discloses a much improved method for locating, differentiating, and removing neoplasms. Such technique utilizes a radiolabeled antibody and a portable radiation detection probe which the surgeon may use intraoperatively in order to detect sites of radioactivity. Because of the proximity of the detection probe to the labeled antibody, the hint radiation emanating from neoplastic tissue at occult sites becomes detectable, for example, in part because of the inherent application of the approximate inverse square law of radiation propagation. The procedure is known as the Radioimmunoguided Surgery.TM. system (Radioimmunoguided Surgery being a trademark of Neoprobe Corporation, Columbus, Ohio) and is successful additionally because of a recognition that tumor detection should be delayed until the blood pool background of circulating radiolabeled antibody has had an opportunity to be cleared from the body. As a consequence, the photon emissions or radiation emitted by minor tumors compared to surrounding tissue becomes detectable in view of the proximity of the probe device to it. Fortuitously, the '840 patent discloses the ability of the radiolabeled antibody to remain bound to or associated with neoplastic tissue for extended periods of time with the radio tag still bound thereto. Moreover, even though the accretion of radioactivity at the tumor site decreases over time, the blood pool background and surrounding tissue (relative to the tumor sites) decrease at a much greater rate so that the radioactive sites can be determined readily utilizing a hand held probe positioned in close proximity with the tissue under investigation.
Somewhat recently, laparoscopic surgery has become popular as an alternative to traditional operative procedures. Particularly with the development of video-based visual systems, laparoscopic surgical techniques have been employed with more complicated gastro-intestinal procedures. Such procedures offer savings in total health care costs as a result of shorter hospital stays and a more rapid patient return to normal activity. However, these procedures require instrumentation and technique supplanting conventional three-dimensional viewing and tactile feedback to the surgeon. Improved instrumentation particularly is called for where these newer surgical techniques are applied to the detection and removal of neoplastic tissue.
While a variety of laparoscopic instruments have been developed, such equipment falls into two broad categories: those major pieces of equipment that enable the surgeon to perform laparoscopy and those instruments related to the performance of specific tasks or procedures, e.g. electrocautery and laser. Generally, visualization within peritoneal cavity requires "space" in which to shine light and maneuver. In a standard surgical approach or laparotomy this space is created by opening the abdomen and allowing room light and air into the cavity to accommodate three-dimensional viewing. In laparoscopic procedures, this is accomplished by filling the peritoneal cavity with a gas that distends the abdominal wall and provides an area for light and manipulation, a process termed "pneumoperitoneum". Carbon dioxide is the standard gas used for pneumoperitoneum. Pneumoperitoneum currently is carded out utilizing an instrument referred to as an insuffiator.
Laparoscopic surgery generally features the establishment of one or more portals of entry into the abdominal cavity. Mechanisms for inserting and removing various instruments through these portals without loss of pneumoperitoneum are necessary. These ports are established by the insertion of a trochar tip through the skin of the patient in conjunction with a port defining cannula or sheath. The trocar is inserted through the lumen of the cannula as an obturator. Typically, the cannulas have a spring-loaded trumpet valve to permit the introduction of instruments into the abdomen and prevent gas from escaping. Conventionally, the size of the cannula sleeve is 1 mm larger in diameter than the corresponding instrument that will traverse it. Diameters for such instruments may reach, for example, 15 mm or larger in extent.
Employment of the laparoscopic surgical technique in conjunction with the surgical staging and resection of neoplastic tissue poses limitations heretofore not encountered by the surgeon. As noted above, when engaged in treating colon and rectal cancer, the surgeon, in addition to such aids as the radioimmunoguided systems, also relies upon sight and palpalion or feel to locate tumor. With laparoscopic surgical procedures, sight is constrained to the two dimensions available at a video screen and palpation or feel essentially is lost. In effect, the surgeon is maneuvering along or manipulating tissue through elongate instrumentation from a distance of about 18 inches away. Thus, the detection and localization of neoplastic tissue calls for laparoscopic instrumentation which effectively replaces palpalion and three-dimensional viewing. With such supporting instrumentation, the surgeon or surgical oncologist may not only seek to resect neoplastic tissue but properly stage cancer patients so that an appropriate mode of therapy can be administered. The latter staging is particularly important in view of the National Institute of Health (NIH) consensus report concerning the administration of adjuvant chemotherapy to appropriately staged patients. "NIH Consensus Conference: Adjuvant Therapy for Patients with Colon and Rectal Cancer", JAMA, 1990; 264:1444-50.